This invention relates to an adjustable boom vang for a sailing vessel.
A sailboat boom vang is an adjustable device or mechanism secured between an intermediate portion of the mainsail boom and a location near the base of the mast. The forward end of the boom is connected to the mast and normally extends at right angles to the vertical mast. In other words, the boom generally rotates in a substantially horizontal plane about the mast. The leading edge of the mainsail is connected to the mast, and the foot of the sail is connected to the boom. Typically, the boom is connected to the mast by a swivel joint, allowing the rear part of the mast to be raised upwardly. The vang generally forms a triangle with the base of the mast and the boom.
A typical vang includes, especially for smaller boats, a multiple purchase block and tackle system including two or more blocks or pulleys attached to the boom, and a single line having one end secured to one of the pulley systems, with the line having a free end which is pulled out and released manually by the sailor. Especially when sailing downwind, air pressure against the mainsail causes the end of the boom to rise, absent any constraint. The vang may be adjusted to lower or adjust the angle of the boom and to control the shape of the sail, especially the trailing edge of the sail.
In the case of many small sailboats, the mast is unstayed, in that there is not external standing rigging to support the mast in an upright vertical position. In such cases, the base of the mast may extend into a reinforced well or pocket in the deck of the boat and is free to rotate around its longitudinal axis, as the boom rotates away from the centerline of the boat, without allowing the mast to tilt from a vertical position. One commercial example of such a sailboat is known as the Laser.
In most multiple purchase vang systems, a releasable cam cleat is provided at the base of to the system in the exit path of the control line, with the free end of the control line being led aft to the cockpit for control by the sailor. A cam cleat comprises a pair of opposed spring loaded jaws which grip the line and prevent it from slipping against the direction of load, or toward the boom. Cam cleats are conventional items, well known to those skilled in the art of sailing. The line can be released between the jaws by lifting the line upwardly and engaged by pulling on the line. One type of especially suitable cam cleat is described in U.S. Pat. No. 4,453,486, assigned to the Harken Inc., incorporated herein by reference. The line can be released by manually raising the line out of engagement between the jaws and can be engaged by lowering the line under tension against the jaws.
FIG. 1 shows a prior art example of a multi-purchase block and tackle system 10 employed as a boom vang between the base of a vertical mast 12 and a horizontal boom 14 with the boom being connected to the mast by a swivel joint 16. The vang 10 is connected to the base of the mast 12 and extends rearwardly and upwardly, with the upper portion being connected to the boom 14 and forming a triangle therebetween. The vang 10 comprises a lower multiple part block system 17 connected to the mast 12 and an upper multiple block system 18 connected to the boom. The bitter end 20 of a line 22 is secured to a stationary part of one of the blocks at 23 and is reeved between the block systems 17 and 18 to provide a mechanical advantage when pulling on the free end 24 of the line 22, and in the example shown, is a four to one ratio or 5 mechanical advantage. The line 22 exits the lower block assembly 16 in alignment with a cam cleat 26 secured to the assembly having opposed jaws which are spring loaded to a closed position to grip the line against the direction of load, or toward the vang. Lower block 17 is attached to the mast by clasp 28 or other loose linkage. Additional blocks and longer lines provide higher ratios as may be desired. Examples of vang systems and component parts for small boats are shown on page 193 of the Harken Inc. 1999 catalog, available from Harken Inc., Pewaukee, Wis.
It may be seen that if the mast 12 and/or boom 14 rotates away from the center line of the boat, as generally illustrated in the plan view of FIG. 2, this will cause twisting of the lower block system 16 and the associated cam cleat 26, such that the free end 24 of the line 22 is out of alignment with the center line between the jaws of the cam cleat. Also, when the vang system is slack, or when load conditions are variable, the cam can move around at an angle to the direction of pull on the line 24. It will be appreciated that boom vangs of this nature can utilize up to a 8 or 9 to 1 ratio, and the forces involved are very substantial. These conditions can make it difficult or impossible for a single sailor, who is steering the boat with one hand, to release and engage the line 24 with the cleat 26. Block 17 may twist or flex as line 24 is pulled on, making re-engagement with cleat 26 impossible. Additionally, movement of block 17 off the centerline of the boat as line 24 is pulled on can cause tangling of the line.
It will be appreciated that this problem exists not only for vangs used with unstayed masts that rotate with the boom, but also for stayed masts that remain stable while the boom pivots away from the boat center line. For these stable masts, the lower vang block will twist and turn in the direction of the pivoting boom, making engagement of the lead line with the block cam cleat difficult or impossible. Additionally, drawing on the lead line will tend to cause the lower vang block to twist away from the boom, sometimes resulting in a tangling of the reeved vang line.
There is thus a heretofor unresolved need in the art for a boom vang system with improved performance when the system is at an angle to the centerline of a boat.
It is an object of the invention to provide a vang base having a rigid tang and a pivotally movable cam arm.
It is a further object of the invention to provide a boom vang system having a rigid tang and a pivotally movable cam arm.
It is a further object of the invention to provide a boom vang system having a rigid tang hingedly attached to the mast, with a cam cleat arm hingedly attached to the rigid tang.
The present invention comprises a vang base for attachment to a sailboat mast; with the vang base comprising a rigid tang for attachment to the mast and a cam cleat arm pivotally attached to the tang, with the cam cleat arm pivotal along an arc about the base. The tang has at least a pulley attached thereto, and the cam cleat arm has at least a cam cleat attached thereto. In a preferred configuration, the tang further comprises an adjustable jaw arm having a jaw, with a pin held in the jaw. The pivotal cam cleat arm further has an ear for pivotal attachment to the pin.
The present invention additionally comprises a boom vang system having at least a boom pulley for attachment to the boom, and a vang base for attachment to the mast. The vang base comprises a rigid tang for attachment to the mast, the tang having at least a pulley, and a cam cleat arm pivotally attached to the tang, the cam cleat arm rotatable along an arc about the tang. Preferably, the cam cleat arm is pivotal along an arc that lies in a plane that is substantially parallel with the boat deck. A cam cleat is attached to the cam cleat arm. A rope having two free ends passes through the cam cleat, through the tang pulley, and through the boom pulley, with one of the two ends connected to one of the boom or the mast.
In an additional embodiment of the invention, a boom vang""s rigid tang is hingedly attached to the mast. The hingedly attached rigid tang has a pivotal cam cleat arm. It will be appreciated that this embodiment of the boom vang of the invention will be of utility for boats having a stayed, stationary mast.
Rather than securing the lower portion of the tackle and cleat system directly to the mast, the vang base and the boom vang system of the present invention thus contemplate the provision of a pivotally mounted cam cleat that allows for rotation along an arc about the vang base. As the mast and boom may swing from the centerline of the boat on boats with an unstayed, rotating mast, the rigid tang statically connected to the mast member prevents or greatly reduces any twisting or flexing of the cleat under various load conditions. The cam cleat arm pivotally attached to the rigid tang allows the control line to be remotely engaged and released from the cleat, since any hauling pressure on the control line will bring the centerline of the pivotally mounted cleat into alignment with the rearwardly extending direction of the control line regardless of the position of the rigid member. Pivoting along a plane parallel to the boat deck further enables easy engagement and disengagement of the lead line from the cam cleat. For boats with a stayed, stationary mast, the embodiment of the vang invention having a rigid tang hingedly attached to the mast allows the vang base to pivot with the boom. The pivotally attached cam cleat arm will allow the cam cleat to easily be oriented in line with a sailor when the lead line is drawn tight.
The boom vang base and the boom vang system of the invention thereby completely eliminate the problems referred to above and allow easy adjustments of the control line, including release and engagement with the cleat, regardless of the position of the boom and regardless of the position of the sailor in the cockpit aft of the mast. The vang fitting for a multipurchase system is especially useful on small boats which are sailed by a single sailor, where any unnecessary movement by the sailor solely to control or adjust the vang line is difficult, inconvenient or impossible, especially under racing conditions.
The above brief description sets forth rather broadly the more important features and advantages of the present disclosure so that the detailed description that follows may be better understood, and so that the present contributions to the art may be better appreciated. There are, of course, additional features of the disclosure that will be described hereinafter which will form the subject matter of the claims appended hereto. In this respect, before explaining the embodiment of the disclosure in detail, it is to be understood that the disclosure is not limited in its application to the details of the construction and the arrangements set forth in the following description or illustrated in the drawings. The present invention is capable of other embodiments and of being practiced and carried out in various ways, as will be appreciated by those skilled in the art. Also, it is to be understood that the phraseology and terminology employed herein are for description and not limitation.